A model for the simultaneous adjustment of GPS pseudorange and carrier beat phase observations in precise kinematic positioning is derived. A sequential least‐squares adjustment algorithm filters the noise of the pseudorange data using the carrier beat phase differences in time (Doppler). GPS system errors such as orbital biases and satellite clock errors are eliminated or reduced by employing a GPS monitor station. If the monitor station results are provided in real time via radio link, a real‐time relative positioning accuracy of better than 1 m is showntobe realistic for moving‐platform applications. Backward smoothing and additionala prioriheight information improve the result to a relative position accuracy level of a few decimeters. Infrequent loss of receiver phase lock is shown to be no serious problem.